This may get a lot worse for every non Chinese phone maker, as they get access to cheap subsidized chips from SMIC that are extremely competitive for low end phones.
Samsung isn't under any sort of pressure. No one is forcing their hand to give updates. Their entry level phones still get 2 years only. Mid level 4 years. Where Samsung loses is price competiveness. Emerging markets are very price conscious. Chinese OEMs offer way better bang for buck than Samsung ever does. Heck, for a random mid level price, a Chinese OEM will give OLED screen, 120 Hz display (which Samsung has only for Flagships) and way faster charging(with an actual charger; and no, I don't believe Samsung gives a darn about the environment by not bundling chargers, they only do so so they can sell their massively overpriced chargers).
I don't think SMIC refuses to sell to non-Chinese companies. Nokia mostly uses Unisoc chips, which are made in China (not sure if by SMIC).
But if they did, it would be a pretty serious problem, since I don't think SMIC even has a viable competitor in the entry-level smartphone chip market.
That lack of competing isn't because of price tho. The CCP has effectively convinced the population that Apple (US phones) are bad/untrustworthy, much like the US government has done regarding Huawei. There was a time when Apple had a decent (not great) marketshare in China.
Apple's collapse in China is the direct consequence of America's anti-China policy. Why would the Chinese buy phones from a country that keeps attacking them with sanctions?